com.cloudera.oryx.als.serving.web.EstimateForAnonymousServlet.java Source code

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Here is the source code for com.cloudera.oryx.als.serving.web.EstimateForAnonymousServlet.java

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/*
 * Copyright (c) 2013, Cloudera, Inc. All Rights Reserved.
 *
 * Cloudera, Inc. licenses this file to you under the Apache License,
 * Version 2.0 (the "License"). You may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * This software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
 * CONDITIONS OF ANY KIND, either express or implied. See the License for
 * the specific language governing permissions and limitations under the
 * License.
 */

package com.cloudera.oryx.als.serving.web;

import java.io.IOException;
import java.io.Writer;
import java.util.Iterator;
import java.util.NoSuchElementException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.math3.util.Pair;

import com.cloudera.oryx.als.common.NoSuchItemException;
import com.cloudera.oryx.als.common.NotReadyException;
import com.cloudera.oryx.als.common.OryxRecommender;

/**
 * <p>Responds to a GET request to
 * {@code /estimateForAnonymous/[toItemID]/[itemID1(=value1)](/[itemID2(=value2)]/...)},
 * and in turn calls {@link OryxRecommender#estimateForAnonymous(String, String[], float[])}
 * with the supplied values. That is, 1 or more item IDs are supplied, which may each optionally correspond to
 * a value or else default to 1.</p>
 *
 * <p>Unknown item IDs are ignored, unless all are unknown, in which case a
 * {@link HttpServletResponse#SC_BAD_REQUEST} status is returned.</p>
 *
 * <p>Outputs the result of the method call as a value on one line.</p>
 *
 * @author Sean Owen
 */
public final class EstimateForAnonymousServlet extends AbstractALSServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {

        CharSequence pathInfo = request.getPathInfo();
        if (pathInfo == null) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST, "No path");
            return;
        }
        Iterator<String> pathComponents = SLASH.split(pathInfo).iterator();
        String toItemID;
        Pair<String[], float[]> itemIDsAndValue;
        try {
            toItemID = pathComponents.next();
            itemIDsAndValue = RecommendToAnonymousServlet.parseItemValuePairs(pathComponents);
        } catch (NoSuchElementException nsee) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST, nsee.toString());
            return;
        }

        if (itemIDsAndValue.getFirst().length == 0) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST, "No items");
            return;
        }

        String[] itemIDs = itemIDsAndValue.getFirst();
        unescapeSlashHack(itemIDs);
        float[] values = itemIDsAndValue.getSecond();

        OryxRecommender recommender = getRecommender();
        try {
            float estimate = recommender.estimateForAnonymous(toItemID, itemIDs, values);
            Writer out = response.getWriter();
            out.write(Float.toString(estimate));
            out.write('\n');
        } catch (NotReadyException nre) {
            response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE, nre.toString());
        } catch (NoSuchItemException nsie) {
            response.sendError(HttpServletResponse.SC_NOT_FOUND, nsie.toString());
        }
    }

}